Tom Mockridge, the News Corp. executive who essentially replaces James Murdoch atop the News International tabloid empire, knows where the bodies are buried: inside a cache of 10 terabytes of email and other documents that he has said he will selectively provide to British police investigating criminal phone and computer hacking at Rupert Murdoch's newspapers.

He previously toiled as the chief of Sky Italia and as James' right-hand man in Asia—far away from London, in other words. A News Corp source told The Guardian, "He is a strong and competent manager. He is not very flappable and is hugely experienced."

But he has also been with the Murdoch empire since 1991, meaning that he's part of that close circle of longtime loyalists and insiders in whom Murdoch has placed much trust.

In fact, long before today's unsurprising departure by James, Mockridge was given perhaps the most sensitive job of all with News Corp.: Selecting for the British police investigation internal emails related to hacking. He told the Leveson inquiry in October that he would not be giving all News Corp.'s email to police:

"Additionally, a major exercize has been conducted in reconstructing and collating a database of historic emails and other documents, consisting of around 10 terabytes worth of data. That restore is nearing completion. … I will ensure that NI will provide material of relevance to the inquiry."

His work has been fruitful. In December, he amended his testimony to say that an arrested News Corp. reporter had been discovered hacking someone's email and was disciplined and then dismissed for an "unrelated matter."

Which begs the question, if hacking is only a disciplinary offense at News, what was the act that got the writer fired?